when you do a return to home the drone will go to a preset height before it turns and flies back to the home point, i believe that this is set at 30mtrs when the app is first started ,it is possible to alter this setting in the app i have mine at 40mtrs to make sure it clears unseen tall trees etc , this feature will work if at the time you pressed RTH and the drone was at less than the preset height ,then it will climb to that height before it returns,if it is above the preset height then it will return at that height,